C# provide five access specifier, they are as follows:
Public is the most common access specifier in C#. It can be access from anywhere that means there is no restriction on accessibility. The scope of the accessibility is inside class as well as outside. The type or member can be accessed by any other code in the same assembly or another assembly that references it.
The scope of the accessibility is limited only inside the classes or struct in which they are declared. The private members cannot be accessed outside the class and it is the least permissive access level.
The scope of accessibility is limited within the class or struct and the class derived (Inherited) from this class.
The internal access modifiers can access within the program that contain its declarations and also access within the same assembly level but not from another assembly.
Protected internal is the same access levels of both protected and internal. It can access anywhere in the same assembly and in the same class also the classes inherited from the same class.